SB-Zusatz 33 - 1937.*SOLD* SB-Zusatz 33.“Schlusszeichen Betrieb” (SB) or End-pulse system.
This system was used where it was important that the switchboard connections could be reused for the next caller as soon as the previous call had ended. Apparently not all callers applied the correct manual calling-off procedure at the end of their call so that the switchboard did not get a signal that the call had ended. By using the automatic end-pulse system, this switchboard was always notified as soon as the handset was replaced.
Dated 1937 & also shows a Luftwaffe acceptance stamp 'BAL' This unit has been rewired at some stage & 2 base screws are missing, otherwise in very good condition.
Photo 5 shows the unit in use. Price is for SB-Zusatz 33 only.